Reversing switching circuit for automatic headlight



H. E. TODD July 7, 1959 REVERSINC SWITCHING CIRCUIT FOR AUTOMATICHEADLIGHT Filed Sept. 18, 1956 INVENTOK 1/ 470M 5: Z'Z ad ATTORNEY.

WARRSQM United States Patent REVERSING SWITCHING CIRCUIT FOR AUTOMATICHEADLIGHT Harold E. Todd, Anderson, Ind., assignor to General MotorsCorporation, Detroit, Mich., a corporation of Delaware Applicati'onSeptember 118, 1956, Serial No. 610,545

3 Claims. (Cl. 31583) This invention relates to control switching meansfor electric lighting systems and more particularly to control switchingmeans for multi-filament headlamps for automotive vehicles.

Automotive vehicles are conventionally equipped with headlamps having abright or long range filament for country driving and a dim or shortrange filament for city driving. A manually operated ratchet type footswitch is conventionally provided to alternatively energize the dim orthe bright filaments depending upon the driving requirements. Morerecently automatic light controlled means have been ofiered forswitching between dim and bright filaments which means is controlled bythe amount of incident light projected on the front of the vehicle fromapproaching cars, said light falling upon a photocell which may bemounted behind the windshield. In installations of automatic lightsensitive control means, it is desirable that the driver be able toobtain at his desire manual control of the headlamp filaments orautomatic control, and further that he be able to obtain opposite beamillumination at any time whether the headlamp filaments may be undermanual or automatic control.

It is therefore an object in making this invention to provide controlswitching means for combined automatic light sensitive and manuallycontrolled multiple filament headlamps.

It is a further object to provide control switching means formulti-filament headlamps which will always energize the alternatefilament upon actuation, whether the filament energization is beingcontrolled by automatic light sensitive means or other means.

It is still a further object to provide control switching means givingreverse beam illumination upon actuation at any time for automaticallycontrolled multi-filament headlamps.

With these and other objects in view, which will become apparent as thespecification proceeds, my invention will be best understood byreference to the following specification and claims and theillustrations in the accompanying drawing in which the drawing is acircuit diagram of a control switching system embodying my invention.

Referring now more particularly to the drawing, there is shown therein apair of headlamps 2 and 4 each of which contains an upper beam filament6 and 8 and a lower beam filament 10 and 12, respectively. Both of thesefilaments in each lamp is connected to a ground return. In order tocontrol the energization of the desired headlamp filaments there isprovided a conventional foot dimmer switch 14 which is a ratchet type ofswitch alternately engaging difierent contacts and remaining in its lastactuated position until physically moved to the opposite contact. Thisprovides a manual control for beam energization. The system alsoincludes an automatic light sensitive control 16 which may be of anysuitable type such, for example, as that shown in Patent 2,679,616issued May 25, 1954, to Onksen et al. In this type of system when nolight falls on the light sensitive unit a sufficiently positive bias isprovided on an electronic tube so that the latter may conduct. Thisportion of the system is shown at tube 18, the output "voltage of thelight sensitive control system 16 being applied to control grid 20 whichin turn controls the flow of current between the cathode 22 and theplate 24 of the double triode tube 18. When light does fall on the lightsensitive uni-t the bias on grid 20 moves in a negative direction totend to cut off conduction through the tube and decrease the current inline 26 connected to the plate 24.

A sensitive control relay 28 having an operating coil 30 also includes amovable armature 32 which oscillates between two fixed contacts 34 and36. The operating coil 30 has one terminal connected to line 26 and theother terminal connected to a suitable source of power indicated as 150volts. Thus when no light falls on the light sensitive control device16, the relay operating coil 30 is energized holding its armature 32 inthe position shown in contact with lower stationary contact 36. On theother hand, when light falls on the light sensitive control device,conduction through the tube 18 is sufficiently decreased that operatingcoil 30 can no longer hold armature 32 in its lower position against aspring bias and armature 32 moves to engage upper contact 34.

Interconnecting the manual ratchet type foot dimmer switch 14 and thelight sensitive control system with the filaments of the headlamps 2 and4 is a compound power relay 38. This section includes a selector relaycoil A and a reversing relay coil B, each of which actuates a pair ofpivoted armatures tied together to move simultaneously. Relay coil Aactuates a selector switch having an armature 42 and an auxiliary switchhaving an armature 40 and both armatures are spring biased upwardly asshown. Relay coil B, on the other hand, actuates armatures 44 and 46which are spring biased upwardly. Armature 40 oscillates betweenstationary contacts 48 and 50 and armature 42 oscillates betweenstationary contacts 52 and 54. Stationary contact 48 is connectedthrough conductive line 56 with cathode 58 of the second triode sectionof duo triode tube 18. Stationary contact 50 is connected through line60 with stationary contact 34 of the sensitive relay 28 and one terminalof the relay coil A. Movable armature 40 is electrically connectedthrough line 62 to stationary contact 64 on the manual ratchet dimmerswitch 14. Armature 42 of the first relay is connected through line 66with one terminal of relay coil A, one terminal of the relay coil B andthe 12 volt source of power such, for example, as the storage battery ofthe vehicle. Stationary contact 52 of the first relay section isconnected directly to armature 44 of the second relay section andstationary contact 54 is likewise connected to armature 46.

Armature 44 oscillates between two stationary contacts 68 and 70,contact 68 being connected through line 72 to one terminal of both lowerbeam filaments 10 and 12. Contact 70 is connected through line 74 withone terminal of both of the upper beam filaments 6 and 8 and also tostationary contact 76 associated with movable armature 46. The remainingterminal of each of the filaments is grounded. Stationary contact 78associated with armature 46 is connected through tie line 80 with line72 and the lower beam filaments. Line 82 connects the remaining terminalof relay coil B with stationary contact 84 on the manual ratchet switch14. Movable armature 86 of switch 14 is grounded and is so mounted as toalternately engage stationary contacts 64 and 84. A pilot light 88 isconnected between the source of power and line 82 to indicate when thedevice is on automatic operation.

The main advantage of this system, the operation of which will bedescribed, is to provide alternate filament energization each time themanual ratchet dimmer switch 14 is actuated and armature 86 is movedfrom one stabetween aL12-volt supply and ground. Relay coil B-will alsobe energized through a circuit from the voltage supply line 66, coil B,line 82, contact 84, armature 86- to. ground; Thus the two armatures 44and 46 will be held" in their lower position as'shown. If no light oronly a small amount'is falling on the light sensitive control unit 16,the first triode section of the tube 18 is sufficiently conductive topermit current flow through the sensitive relay coil 3tl-so thatarmature 32 is drawn to the position shown. Since armature 32 does notengage contact 34, relay coil A is deenergized. Under these conditionsthe high beam filaments 6 and 8 should be illuminated. This energizingcircuit can be traced from the 12 volt supply through line 66, armature42, power contact 52, armature 44, contact 7 line 74 through both highbeam filaments 6 and 8 to ground. If under these conditions the operatordesires low beam illumination, he operates switch 14 which moves thearmature 86 away from engagement with contact 84 into engagement withcontact 64. This breaks the energization circuit for relay coil B andarmatures 44 and 46 are drawn back to engage the upper contacts 68 and76 instead of contacts 70 and 78 respectively. At this time the secondsection of tube 18 will conduct closing relay coil 31) independent oflight intensity on light sensitivity control. This circuit is fromground to armature 86, to contact 64, to line 62, armature 40, tocontact 48, to line '56, to cathode 58, to plate 90, to line 26, and tocoil 30. Since both coils A and B are deenergized, the circuit for thelow beam filament energization and illumination which was desired can betraced as follows: from the source of power line 66, armature 42,contact 52, armature 44, contact 68, line 72 through low beam filaments12 and 18 to ground. This gives low beam illumination or reverseoperation at the will of the driver. Any movement of armature 8617ctween contacts 64 and 84 merely moves armatures 44 and 46 between thestationary contacts and switches high and low beam at will as long as nolight falls on the light sensitive control.

If light falls on the light sensitive control device 16 and the armature86 is in the position shown, then the conductivity of the first triodesection of the tube 18 is decreased and relay coil 30 releases itsarmature 32 which moves up into engagement with stationary contact 34.This completes an obvious circuit through relay coil A and under theseconditions both coil A and coil B are energized. At this instant acircuit is completed to the beam filaments due to the fact that light isfalling on. the photocell. This circuit may be traced as follows fromthe source of power, line 66, armature 42, contact 54, armature 46,contact '78, line 80, line 72 to the low beam filaments and 12, audioground. The automatic control therefore requires lower beam.illumination at this time. If now the operator desires to overrule theautomatic control and obtain high beam illumination, he again actuatesmanual foot dimmer switch 14 to move armature 86 to engage contact 64.This breaks the energizing circuit for relay coil B and its armatures 44and 46 will be withdrawn by the spring bias to move to' their rear orupper contacts completing switching from low beam to high beam asdesired.

One other possibility will now be described wherein it the armature 86of the foot switch 14 is in its left hand or manual operation positionin contact with 64'. Under those conditions relay coil B will remaindeenergized; If it is first assumed that no light is. falling on thelight sensitive control then relay coil 38 will be energized to attractits armature 32 and relay coil- A will likewise be deenergized; Underthese conditions thelower" beam-filaments12 and 10 areenergized-throughthe foltionary contact 52, armature 44, stationary contact 68,

line 72, filaments 10 and 12 to ground. If the operator" now desires toobtain the opposite beam energization of filaments he actuates switch 14again which completes an energizing circuit through coil B whichattracts its armatures 44 and 46 which switch the beam filaments aspreviously described. Relay coil A at this time still remainsdeenergizeddue to the fact that armature 32 is maintained in its attractedposition.

Finally, if armature 86 is in the left hand position in contact withstationary contact 64, relay coil A will be energized throughtwogrounding circuits, one through line 60, contact 50, armature 40,line 62, contact 64, armature 86 to ground and if light is falling onthe light sensitive control device to deenergizecoil 30 allowing it torelease its armature 32, also through this armature to ground. Then coilA will be energized and coil B will be deenergized. At this time thesystem is under manual control and the high beam filaments 10 and 12will be energized through the following circuit: source of power, line66, armature 42, contact 54, armature 46,

contact 76, line 74 and high beam filaments 6 and 8 to ground. If it isnow desired under these circumstances to obtain low beam illumination,the operator moves. armature 86 back to the position shown completing anenergization circuit for relay coil B and, under these conditions, coilsA and B are both enengized. The energization of relay coil B willaccomplish the desired switching from high to low beam by movingarmatures 44 and 46 down into engagement with the lower contacts.Movement of the manual dimmer switch armature 86 away from contact 64breaks one energizing grounding circuit for relay coil A, but with lightfalling on the light sensitive control device 16, the current flowthrough sensitive relay coil 30 is reduced to release its armature 32 sothat it makes. contact with contact 34 and completes another enengizingcircuit to relay coil A to maintain it energized and thus oppositebeamillumination will again be obtained by actuation of manual ratchetswitch 14.

Under the immediately preceding conditions of moving manual armature 86from engagement with contact 64 to engagement with contact 84 and ifno'light has been falling on the light sensitive control, there exists aslightly different set of circumstances. Relay coil A and coil B areboth deenergized and the lower beam filaments are energized. Engagementof the armature,

86 with contact 84 again energizes relay coil cap B. 1

With no light falling on light sensitive control 16, relay coil 30 isenergized and it holds its armature 32 in the lower position. Thu-sthere is no energizing circuit for relay coil A and its armatures. 40and 42 are in the back position while armatures 44 and 46 are moveddownwardly to switch to high beam filaments 6 and 8. Thus again areverse filament energization is obtained.

From the above description it will be obvious that when the manualswitch 14 is in the position shown, the

headlights are under automatic control and the pilot light 88 is lit toindicate this condition. When the foot dimmer switch is in its leftposition, the system is under manual control and the foot switch must beactuated to obtain alternate beam illumination, but under any conditionactuation of the foot dimmer switch will always illuminate the alternatefilaments to provide the opposite type of illumination.

I claim:

1. In a control system for vehicle headlamps, upper and lower beamfilaments, a voltage source, a selector relay and a two positionselector switch actuated thereby and connected with the voltage source,a reversing relay and a two position reversing switch actuated therebyand connected between the selector switch and the filaments, a dimmerswitch movable between automatic and manual positions and beingconnected'with the reversing; 1 relay whereby each actuation of thedimmer switchto ground and movable between causes a different filamentto be connected to the voltage source through the reversing switch, alight sensitive control circuit including a control relay and a controlswitch actuated thereby and connected with the selector relay to causeactuation of the selector switch in accordance with incident lightintensity and selectively connect one of the filaments with the voltagesource through the reversing switch when the dimmer switch is in theautomatie" position, and auxiliary switch actuated by the selector relayand being connected with the dimmer switch, a holding circuit for theselector relay including saiddimmer switch in the manual position andthe auxiliary switch when the selector switch is in one position, and aholding circuit for the control relay including the dimmer switch in themanual position and the auxiliary switch when the selector switch is inthe other position.

2. In a controlsystem for vehicle headlamps, upper and lower beamfilaments, a voltage source having one terminal connected to ground, aselector relay and a two position selector switch actuated thereby andconnected with the other terminal of the voltage source, a reversingrelay and a two position reversing switch actuated thereby and connectedbetween the selector switch and the filaments, said relays each havingone terminal connected with the other terminal of the voltage source, adimmer switch having an armature contact connected automatic and manualpositions and engaging first and second contacts respectively, saidfirst contact being connected with the other terminal of the reversingrelay whereby each actuation of the dimmer switch causes a differentfilament to be connected with the reversing switch, a light sensitivecontrol circuit including a control relay, means applying a voltage toone terminal of the control relay, a control switch actuated by thecontrol relay and connecting the other terminal of the selector relay toground to cause actuation of the selector switch in accordance withincident light intensity and selectively connect one of the filamentswith the voltage source through the reversing switch, and means toprevent actuation of the selector switch when the dimmer switch is inthe manua position, said means comprising an auxiliary switch actuatedby the selector relay and having a movable contact and first and secondfixed contacts, the movable contact of the auxiliary switch beingconnected with the second fixed contact of the dimmer switch, the firstfixed contact of the auxiliary switch being connected with said otherterminal of the selector relay to complete a holding circuit thereforwhen the selector switch is in one position, the second fixed contact ofthe auxiliary switch being connected with the other terminal of thecontrol relay h to complete a holding circuit therefor when the selectorswitch is in the other position.

3. In a control system for vehicle headlamps, upper and lower beamfilaments, a voltage source having one terminal connected to ground, aselector relay and a selector switch actuated thereby and having amovable contact connected with the voltage source and a pair of fixedcontacts, a reversing relay and a reversing switch actuated thereby andhaving a pair of movable contacts connected with respective fixedcontacts of the selector switch, the reversing switch also havingassociated with each of its movable contacts a pair of fixed contacts,one of each pair being connected to one filament and the other of eachpair being connected with the other filament, said relays each havingone terminal connected with the other terminal of the voltage source, adimmer switch having an armature contact connected to ground and movablebetween automatic and manual positions and engaging first and secondcontacts respectively, said first contact being connected with the otherterminal of the reversing relay whereby each actuation of the dimmerswitch causes a different filament to be com nected to the voltagesource through the reversing switch, a light sensitive control circuitincluding a control relay,- means applying a voltage to one terminal ofthe control relay, a control switch actuated by the control relay andconnecting the other terminal of the selector relay to ground to causeactuation of the selector switch in accordance with incident lightintensity to selectively connect one of the filaments with the voltagesource through the reversing switch, and means to prevent actuation ofthe selector switch when the dimmer switch is in the manual position,said means comprising an auxiliary switch actuated by the selector relayand having a movable contact and first and second fixed contacts, themovable contact of the auxiliary switch being connected with the secondfixed contact of the dimmer switch, the first fixed contact of theauxiliary switch being connected with the said other terminal of theselector relay to complete a holding circuit therefor when the selectorswitch is in one position, the second fixed contact of the auxiliaryswitch being connected with the other terminal of the control relay tocomplete a holding circuit therefor when the selector switch is in theother position.

References Cited in the file of this patent UNITED STATES PATENTS2,431,394 Friedman Nov. 25, 1947 2,679,616 Onksen et al May 25, 19542,761,995 Du Rocker Sept. 4, 1956 2,825,851 Lidiak Mar. 4, 1958

